String Inverter Reference Design
An illustrative control / communication board reference design for string inverters (3–350 kW) on the PV generation side: a DSP controls multi-MPPT boost and three-level inversion; the external RS-485 (meter / parallel units / data logger stick) and Ethernet ports both have high isolation and surge protection, and DC-side AFCI arc detection is sampled by a high-frequency current transformer. Power-stage parts are selected separately for the bus voltage; this page marks the VOOHU parts available on the control / communication board.
Illustrative PCB ⇄ Schematic
Illustrative top-side view arranged by functional zone (not the actual layout). Red numbered dots mark positions VOOHU can supply. Click a component on the board, an entry in the index below or a part in the schematic to see recommended parts and package pinouts on the right.
Illustrative RS-485 topology: the MCU UART is converted to a differential signal by isolated transceiver U3, then passes in turn the stage-2 clamp ESD D1 (WHALD30E2B), the signal-line common-mode choke L1 (WHAC-4532A-510U0) and the stage-1 3-pole gas discharge tube GDT1 (WHGT090V1P0A, center electrode to chassis ground) to RJ45 J1; the isolated side of the transceiver is powered by the push-pull isolated supply. Termination / bias resistors depend on bus length and node count; they are drawn as symbols without values.
Board bill of materials
Summarized by position; click any row to locate it on the board above.
| No. | Zone | Position | Ref. | VOOHU category | Recommended part | Availability |
|---|---|---|---|---|---|---|
| 01 | A RS-485 (isolated) | RS-485 RJ45 1×2 (meter / parallel operation) | J1 | RJ45 Connector | WH56I3288RGGG0121101 | VOOHU |
| 02 | A RS-485 (isolated) | RS-485 GDT ×2 | GDT1 | GDT | WHGT090V1P0A | VOOHU |
| 03 | A RS-485 (isolated) | RS-485 CMC ×2 | L1 | Signal Line Common Mode Chokes | WHAC-4532A-510U0 | VOOHU |
| 04 | A RS-485 (isolated) | RS-485 ESD / TVS ×2 | D1 | TVS ESD | WHALD30E2B | VOOHU |
| 05 | A RS-485 (isolated) | Isolated RS-485 transceiver ×2 | U3 | — | — | Non-VOOHU |
| 06 | A RS-485 (isolated) | Push-pull driver + rectifier / LDO | U5 | — | — | Non-VOOHU |
| 07 | A RS-485 (isolated) | Push-pull isolation transformer | T1 | Push-Pull Transformers | WHST06K02A0 | VOOHU |
| 08 | B Ethernet | RJ45 port (Modbus TCP / monitoring) | J2 | RJ45 Connector | WH56A31882021103 | VOOHU |
| 09 | B Ethernet | Ethernet port gas discharge tube | GDT2 | GDT | WHGD090V1P0B | VOOHU |
| 10 | B Ethernet | 10/100 LAN transformer (high isolation) | T3 | LAN Transformers | WHSH16F01D4 | VOOHU |
| 11 | B Ethernet | Eth ESD array | D2 | TVS ESD | WHALD03G4U | VOOHU |
| 12 | B Ethernet | 10/100 PHY | U4 | Ethernet PHY | JL1101BR-NI | VOOHU |
| 13 | C DC-side sensing | AFCI arc-detection current transformer | T2 | Current Transformers | WHPT-EP100-018 | VOOHU |
| 14 | C DC-side sensing | AFCI front end (band-pass + ADC) | U8 | — | — | Non-VOOHU |
| 15 | C DC-side sensing | String DC current sensor (Hall) | U9 | — | — | Non-VOOHU |
| 16 | D Control core | DSP (MPPT + grid-tie control) | U1 | — | — | Non-VOOHU |
| 17 | D Control core | Firmware flash | U2 | — | — | Non-VOOHU |
| 18 | E 12 V board power | 12 V power input (from auxiliary power board) | J3 | — | — | Non-VOOHU |
| 19 | E 12 V board power | Input power-line common-mode choke | L3 | Power Line Common Mode Chokes | WHAL-7060A-102T0 | VOOHU |
| 20 | E 12 V board power | Buck converter (12 V → 5 V) | U6 | — | — | Non-VOOHU |
| 21 | E 12 V board power | Buck converter (5 V → 3.3 V / core) | U7 | — | — | Non-VOOHU |
| 22 | E 12 V board power | Molded inductors ×2 (DC-DC) | L4 L5 | Molded Inductors | WHYT0630 Series | VOOHU |
Resources & downloads
Board bill of materials
Reference designators, zones, VOOHU categories, recommended parts and availability for all 22 positions. Opens directly in Excel.
Datasheet collection
Datasheet PDFs for the VOOHU parts recommended on this board.
Design files & footprint library
Schematic, PCB, and VOOHU part footprints and 3D models.
Coming soonRequest the string inverter reference design full package
Includes the full-board position list, datasheets for the recommended VOOHU parts and position-by-position selection notes. For advice tailored to your power class (residential / C&I / utility-scale), number of communication ports or AFCI scheme, please include it in your requirements. We reply within 24 hours on working days.
